Catalysts For The Production Of Acrylic Acid Or Its Derivatives

ABSTRACT

Catalysts for dehydrating hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof to acrylic acid, acrylic acid derivatives, or mixtures thereof with high yield and selectivity, short residence time, and without significant conversion to undesired side products, such as, for example, acetaldehyde, propionic acid, and acetic acid, are provided. The catalysts are mixed protonated monophosphates. Methods of preparing the catalysts are also provided.

FIELD OF THE INVENTION

The present invention generally relates to catalysts useful for theconversion of hydroxypropionic acid, hydroxypropionic acid derivatives,or mixtures thereof to acrylic acid, acrylic acid derivatives, ormixtures thereof. More specifically, the invention relates to catalystsuseful for the dehydration of hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof to acrylic acid, acrylic acidderivatives, or mixtures thereof with high yield and selectivity toacrylic acid, acrylic acid derivatives, or mixtures thereof, shortresidence time, and without significant conversion of thehydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof to undesired side products, such as, for example, acetaldehyde,propionic acid, acetic acid, 2,3-pentanedione, carbon dioxide, andcarbon monoxide.

BACKGROUND OF THE INVENTION

Acrylic acid, acrylic acid derivatives, or mixtures thereof have avariety of industrial uses, typically consumed in the form of polymers.In turn, these polymers are commonly used in the manufacture of, amongother things, adhesives, binders, coatings, paints, polishes,detergents, flocculants, dispersants, thixotropic agents, sequestrants,and superabsorbent polymers, which are used in disposable absorbentarticles, including diapers and hygienic products, for example. Acrylicacid is commonly made from petroleum sources. For example, acrylic acidhas long been prepared by catalytic oxidation of propylene. These andother methods of making acrylic acid from petroleum sources aredescribed in the Kirk-Othmer Encyclopedia of Chemical Technology, Vol.1, pgs. 342-369 (5^(th) Ed., John Wiley & Sons, Inc., 2004).Petroleum-based acrylic acid contributes to greenhouse emissions due toits high petroleum derived carbon content. Furthermore, petroleum is anon-renewable material, as it takes hundreds of thousands of years toform naturally and only a short time to consume. As petrochemicalresources become increasingly scarce, more expensive, and subject toregulations for CO₂ emissions, there exists a growing need for bio-basedacrylic acid, acrylic acid derivatives, or mixtures thereof that canserve as an alternative to petroleum-based acrylic acid, acrylic acidderivatives, or mixtures thereof.

Many attempts have been made over the last 40 to 50 years to makebio-based acrylic acid, acrylic acid derivatives, or mixtures thereoffrom non-petroleum sources, such as lactic acid (also known as2-hydroxypropionic acid), 3-hydroxypropionic acid, glycerin, carbonmonoxide and ethylene oxide, carbon dioxide and ethylene, and crotonicacid. From these non-petroleum sources, only lactic acid is producedtoday in high yield from sugar (≧90% of theoretical yield, orequivalently, ≧0.9 g of lactic acid per g of sugar) and purity, andeconomics which could support producing acrylic acid at a costcompetitive to petroleum-based acrylic acid. As such, lactic acid orlactate presents a real opportunity of serving as a feedstock forbio-based acrylic acid, acrylic acid derivatives, or mixtures thereof.Also, 3-hydroxypropionic acid is expected to be produced at commercialscale in a few years, and as such, 3-hydropropionic acid will presentanother real opportunity of serving as feedstock for bio-based acrylicacid, acrylic acid derivatives, or mixtures thereof. Sulfate salts;phosphate salts; mixtures of sulfate and phosphate salts; bases;zeolites or modified zeolites; metal oxides or modified metal oxides;and supercritical water are the main catalysts which have been used todehydrate lactic acid or lactate to acrylic acid, acrylic acidderivatives, or mixtures thereof in the past with varying success.

For example, U.S. Pat. No. 4,786,756 (issued in 1988), describes thevapor phase dehydration of lactic acid or ammonium lactate to acrylicacid using aluminum phosphate (AlPO₄) treated with an aqueous inorganicbase as a catalyst. As an example, the '756 patent discloses a maximumyield of acrylic acid of 43.3% when lactic acid was fed into the reactorat approximately atmospheric pressure, and a respective yield of 61.1%when ammonium lactate was fed into the reactor. In both examples,acetaldehyde was produced at yields of 34.7% and 11.9%, respectively,and other side products were also present in large quantities, such as,propionic acid, CO, and CO₂. Omission of the base treatment causedincreased amounts of the side products. Another example is Hong et al.(2011) Appl. Catal. A: General 396:194-200, who developed and testedcomposite catalysts made with Ca₃(PO₄)₂ and Ca₂(P₂O₇) salts with aslurry-mixing method. The catalyst with the highest yield of acrylicacid from methyl lactate was the 50%-50% (by weight) catalyst. Ityielded 68% acrylic acid, about 5% methyl acrylate, and about 14%acetaldehyde at 390° C. The same catalyst achieved 54% yield of acrylicacid, 14% yield of acetaldehyde, and 14% yield of propionic acid fromlactic acid.

Prof. D. Miller's group at Michigan State University (MSU) publishedmany papers on the dehydration of lactic acid or lactic acid esters toacrylic acid and 2,3-pentanedione, such as, Gunter et al. (1994) J.Catalysis 148:252-260; and Tam et al. (1999) Ind. Eng. Chem. Res.38:3873-3877. The best acrylic acid yields reported by the group wereabout 33% when lactic acid was dehydrated at 350° C. over low surfacearea and pore volume silica impregnated with NaOH. In the sameexperiment, the acetaldehyde yield was 14.7% and the propionic acidyield was 4.1%. Examples of other catalysts tested by the group wereNa₂SO₄, NaCl, Na₃PO₄, NaNO₃, Na₂SiO₃, Na₄P₂O₇, NaH₂PO₄, Na₂HPO₄,Na₂HAsO₄, NaC₃H₅O₃, NaOH, CsCl, Cs₂SO₄, KOH, CsOH, and LiOH. In allcases, the above referenced catalysts were tested as individualcomponents, not in mixtures. Finally, the group suggested that the yieldto acrylic acid is improved and the yield to the side products issuppressed when the surface area of the silica support is low, reactiontemperature is high, reaction pressure is low, and residence time of thereactants in the catalyst bed is short.

Finally, the Chinese patent application 200910054519.7 discloses the useof ZSM-5 molecular sieves modified with aqueous alkali (such as, NH₃,NaOH, and Na₂CO₃) or a phosphoric acid salt (such as, NaH₂PO₄, Na₂HPO₄,LiH₂PO₄, LaPO₄, etc.). The best yield of acrylic acid achieved in thedehydration of lactic acid was 83.9%, however that yield came at verylong residence times.

Therefore, the manufacture of acrylic acid, acrylic acid derivatives, ormixtures thereof from lactic acid or lactate by processes, such as thosedescribed in the literature noted above, has demonstrated: 1) yields ofacrylic acid, acrylic acid derivatives, or mixtures thereof notexceeding 70%; 2) low selectivities of acrylic acid, acrylic acidderivatives, or mixtures thereof, i.e., significant amounts of undesiredside products, such as, acetaldehyde, 2,3-pentanedione, propionic acid,CO, and CO₂; 3) long residence times in the catalyst beds; and 4)catalyst deactivation in short time on stream (TOS). The side productscan deposit onto the catalyst resulting in fouling, and premature andrapid deactivation of the catalyst. Further, once deposited, these sideproducts can catalyze other undesired reactions, such as polymerizationreactions. Aside from depositing on the catalysts, these side products,even when present in only small amounts, impose additional costs inprocessing acrylic acid (when present in the reaction product effluent)in the manufacture of superabsorbent polymers (SAP), for example. Thesedeficiencies of the prior art processes and catalysts render themcommercially non-viable.

Accordingly, there is a need for catalysts and methods for thedehydration of hydroxypropionic acid, hydroxypropionic acid derivatives,or mixtures thereof to acrylic acid, acrylic acid derivatives, ormixtures thereof, with high yield, selectivity, and efficiency (i.e.,short residence time), and high longevity catalysts.

SUMMARY OF THE INVENTION

A catalyst for dehydrating hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof to acrylic acid, acrylic acidderivatives, or mixtures thereof is provided. In one embodiment of thepresent invention, the catalyst includes: (a) monohydrogen monophosphatedescribed by formula (I)

[HPO₄]²⁻  (I),

(b) dihydrogen monophosphate anions described by formula (II):

[H₂PO₄]⁻  (II),

and (c) at least two different cations, wherein the catalyst isessentially neutrally charged; and further, wherein the molar ratio ofsaid monohydrogen monophosphate anion to said dihydrogen monophosphateanion in said catalyst is between about 0.1 and about 10.

In another embodiment of the present invention, the catalyst includesthe monophosphate salts described by both formulae (III) and (IV):

M^(II)HPO₄  (III),

M^(I)H₂PO₄  (IV), and

wherein M^(I) is a monovalent cation and M^(II) is a divalent cation.

In yet another embodiment of the present invention, the catalystincludes a monophosphate salt described by formula (V):

M^(II) _(2-x)M^(I) _(x)H_(x)H_(x)(HPO₄)₂  (V),

wherein M^(I) is a monovalent cation and M^(II) is a divalent cation;and wherein x is greater than about 0.2 and smaller than about 1.8.

In another embodiment of the present invention, there is provided amethod of preparing the catalyst. The method includes mixing at leasttwo phosphorus-containing compounds, wherein each said compound isdescribed by one of formulae (VI) to (XXV), or any of the hydrated formsof said formulae:

M^(I) _(a)(H_(3-a)PO₄)  (VI)

M^(II) _(a)(H_(3-a)PO₄)₂  (VII)

M^(III) _(a)(H_(3-a)PO₄)₃  (VIII)

M^(IV) _(a)(H_(3-a)PO₄)₄  (IX)

M^(II) _(b)(OH)_(c)(PO₄)_(d)  (X)

M^(III) _(e)(OH)_(f)(PO₄)_(g)  (XI)

M^(II)M^(I)PO₄  (XII)

M^(III)M^(I) ₃(PO₄)₂  (XIII)

M^(IV) ₂M^(I)(PO₄)₃  (XIV)

M^(I) _(h)H_(4-h)P₂O₇  (XV)

M^(II) _(i)H_((4-2i))P₂O₇  (XVI)

M^(IV)P₂O₇  (XVII)

M^(III)M^(I)P₂O₇  (XVIII)

M^(I)H_(j)(PO₃)_((1+j))  (XIX)

M^(II)H_(j)(PO₃)_((2+j))  (XX)

M^(III)H_(j)(PO₃)_((3+j))  (XXI)

M^(IV)H_(j)(PO₃)_((4+j))  (XXII)

M^(II) _(k)M^(I) _(l)(PO₃)_(r)  (XXIII)

M^(III) _(q)M^(I) _(p)(PO₃)_(s)  (XXIV)

P₂O₅  (XXV)

wherein M^(I) is a monovalent cation; wherein M^(II) is a divalentcation; wherein M^(III) is a trivalent cation; wherein M^(IV) is atetravalent cation; wherein a is 0, 1, 2, or 3; wherein h is 0, 1, 2, 3,or 4; wherein i is 0, 1, or 2; wherein j is 0 or any positive integer;and wherein b, c, d, e, f, g, k, l, m, n, p and q are any positiveintegers, such that the equations: 2b=c+3d, 3e=f+3g, r=2k+1, and s=3q+pare satisfied.

In yet another embodiment of the present invention, there is provided amethod of preparing the catalyst. The method includes mixing andheating: (a) at least one phosphorus-containing compound, wherein eachsaid compound is described by one of formulae (VI) to (XXV), or any ofthe hydrated forms of said formulae:

M^(I) _(a)(H_(3-a)PO₄)  (VI)

M^(II) _(a)(H_(3-a)PO₄)₂  (VII)

M^(III) _(a)(H_(3-a)PO₄)₃  (VIII)

M^(IV) _(a)(H_(3-a)PO₄)₄  (IX)

M^(II) _(b)(OH)_(c)(PO₄)_(d)  (X)

M^(III) _(e)(OH)_(f)(PO₄)_(g)  (XI)

M^(II)M^(I)PO₄  (XII)

M^(III)M^(I) ₃(PO₄)₂  (XIII)

M^(IV) ₂M^(I)(PO₄)₃  (XIV)

M^(I) _(h)H_(4-h)P₂O₇  (XV)

M^(II) _(i)H_((4-2i))P₂O₇  (XVI)

M^(IV)P₂O₇  (XVII)

M^(III)M^(I)P₂O₇  (XVIII)

M^(I)H_(j)(PO₃)_((1+j))  (XIX)

M^(II)H_(j)(PO₃)_((2+j))  (XX)

M^(III)H_(j)(PO₃)_((3+j))  (XXI)

M^(IV)H_(j)(PO₃)_((4+j))  (XXII)

M^(II) _(k)M^(I) _(l)(PO₃)_(r)  (XXIII)

M^(III) _(q)M^(I) _(p)(PO₃)_(s)  (XXIV)

P₂O₅  (XXV)

wherein M^(I) is a monovalent cation; wherein M^(II) is a divalentcation; wherein M^(III) is a trivalent cation; wherein M^(IV) is atetravalent cation; wherein a is 0, 1, 2, or 3; wherein h is 0, 1, 2, 3,or 4; wherein i is 0, 1, or 2; wherein j is 0 or any positive integer;and wherein b, c, d, e, f, g, k, l, m, n, p and q are any positiveintegers, such that the equations: 2b=c+3d, 3e=f+3g, r=2k+l, and s=3q+pare satisfied; and (b) at least one non-phosphorus-containing compoundselected from the group consisting of nitrate salts, carbonate salts,acetate salts, metal oxides, chloride salts, sulfate salts, and metalhydroxides, wherein each said compound is described by one of formulae(XXVI) to (L), or any of the hydrated forms of said formulae:

M^(I)NO₃  (XXVI)

M^(II)(NO₃)₂  (XXVII)

M^(III)(NO₃)₃  (XXVIII)

M^(I) ₂CO₃  (XXIX)

M^(II)CO₃  (XXX)

M^(III) ₂(CO₃)₃  (XXXI)

(CH₃COO)M^(I)  (XXXII)

(CH₃COO)₂M^(II)  (XXXIII)

(CH₃COO)₃M^(III)  (XXXIV)

(CH₃COO)₄M^(IV)  (XXXV)

M^(I) ₂O  (XXXVI)

M^(II)O  (XXXVII)

M^(III) ₂O₃  (XXXVIII)

M^(IV)O₂  (XXXIX)

M^(I)Cl  (XL)

M^(II)Cl₂  (XLI)

M^(III)Cl₃  (XLII)

M^(IV)Cl₄  (XLIII)

M^(I) ₂SO₄  (XLIV)

M^(II)SO₄  (XLV)

M^(III) ₂(SO₄)₃  (XLVI)

M^(IV)(SO₄)₂  (XLVII)

M^(I)OH  (XLVIII)

M^(II)(OH)₂  (XLIX)

M^(III)(OH)₃  (L).

In another embodiment of the present invention, there is provided amethod for preparing the catalyst. The method includes contacting: (a) agaseous mixture comprising water, with (b) a mixture of compoundscomprising at least one condensed phosphate anion selected from thegroup consisting of formulae (LI) to (LIII),

[P_(n)O_(3n+1)]^((n+2)−)  (LI)

[P_(n)O_(3n)]^(n−)  (LII)

[P_((2m+n))O_((5m+3n))]^(n−)  (LIII)

wherein n is at least 2; wherein m is at least 1; wherein, said mixtureof compounds is essentially neutrally charged; and further, wherein themolar ratio of phosphorus to said at least one monovalent cation and atleast one polyvalent cation in said catalyst is between about 0.7 andabout 1.7.

In another embodiment of the present invention, a method of preparing acatalyst is provided including combining BaHPO₄ and KH₂PO₄ in a molarratio between about 3:2 and about 2:3 to form a solid mixture, andgrinding said solid mixture to produce said catalyst.

In another embodiment of the present invention, a method of preparing acatalyst is provided including the following steps: (a) combining BaHPO₄and KH₂PO₄ in a molar ratio between about 3:2 and about 2:3 to form asolid mixture; (b) grinding said solid mixture to produce a mixedpowder; (c) calcining said mixed powder at about 550° C. to produce acondensed phosphate mixture; and (d) contacting said condensed phosphatemixture with a gaseous mixture comprising water and lactic acid at atemperature of about 350° C. and a total pressure of about 25 bar toproduce said catalyst, and wherein the partial pressure of water in saidgaseous mixture is about 12.5 bar.

In another embodiment of the present invention, a method of preparing acatalyst is provided including the following steps: (a) combiningK₂HPO₄, Ba(NO₃)₂, H₃PO₄, and water to form a wet mixture, wherein themolar ratio of Ba(NO₃)₂, K₂HPO₄, and H₃PO₄ is about 3:1:4; (b) heatingsaid wet mixture to about 80° C. with stirring until near dryness toform a wet solid; (c) calcining said wet solid stepwise at about 50° C.,about 80° C., about 120° C., and about 450° C. to about 550° C. toproduce a dried solid; and (d) contacting said dried solid with agaseous mixture comprising water and lactic acid at a temperature ofabout 350° C. and a total pressure of about 25 bar to produce saidcatalyst, and wherein the partial pressure of water in said gaseousmixture is about 12.5 bar.

Additional features of the invention may become apparent to thoseskilled in the art from a review of the following detailed description,taken in conjunction with the examples.

DETAILED DESCRIPTION OF THE INVENTION I Definitions

As used herein, the term “monophosphate” or “orthophosphate” refers toany salt whose anionic entity, [PO₄]³⁻, is composed of four oxygen atomsarranged in an almost regular tetrahedral array about a centralphosphorus atom.

As used herein, the term “condensed phosphate” refers to any saltscontaining one or several P—O—P bonds generated by corner sharing of PO₄tetrahedra.

As used herein, the term “polyphosphate” refers to any condensedphosphates containing linear P—O—P linkages by corner sharing of PO₄tetrahedra leading to the formation of finite chains.

As used herein, the term “oligophosphate” refers to any polyphosphatesthat contain five or less PO₄ units.

As used herein, the term “cyclophosphate” refers to any cyclic condensedphosphate constituted of two or more corner-sharing PO₄ tetrahedra.

As used herein, the term “ultraphosphate” refers to any condensedphosphate where at least two PO₄ tetrahedra of the anionic entity sharethree of their corners with the adjacent ones.

As used herein, the term “cation” refers to any atom or group ofcovalently-bonded atoms having a positive charge.

As used herein, the term “anion” refers to any atom or group ofcovalently-bonded atoms having a negative charge.

As used herein, the term “monovalent cation” refers to any cation with apositive charge of +1.

As used herein, the term “polyvalent cation” refers to any cation with apositive charge equal or greater than +2.

As used herein, the term “heteropolyanion” refers to any anion withcovalently bonded XO_(P) and YO_(r) polyhedra, and thus includes X—O—Y,and possibly X—O—X and Y—O—Y bonds, wherein X and Y represent any atoms,and wherein p and r are any positive integers.

As used herein, the term “heteropolyphosphate” refers to anyheteropolyanion, wherein X represents phosphorus (P) and Y representsany other atom.

As used herein, the term “phosphate adduct” refers to any compound withone or more phosphate anions and one or more non-phosphate anions thatare not covalently linked.

As used herein, the terms “LA” refers to lactic acid, “AA” refers toacrylic acid, “AcH” refers to acetaldehyde, and “PA” refers to propionicacid.

As used herein, the term “particle span” refers to a statisticalrepresentation of a given particle sample and is equal to(D_(v,0.90)−D_(v,0.10))/D_(v,0.50). The term “median particle size” orD_(v,0.50) refers to the diameter of a particle below which 50% of thetotal volume of particles lies. Further, D_(v,0.10) refers to theparticle size that separates the particle sample at the 10% by volumefraction and D_(v,0.90), is the particle size that separates theparticle sample at the 90% by volume fraction.

As used herein, the term “conversion” in % is defined as[hydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof flow rate in (mol/min)−hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof flow rate out(mol/min)]/[hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof flow rate in (mol/min)]*100. For the purposes of thisinvention, the term “conversion” means molar conversion, unlessotherwise noted.

As used herein, the term “yield” in % is defined as [product flow rateout (mol/min)/hydroxypropionic acid, hydroxypropionic acid derivatives,or mixtures thereof flow rate in (mol/min)]*100. For the purposes ofthis invention, the term “yield” means molar yield, unless otherwisenoted.

As used herein, the term “selectivity” in % is defined as[Yield/Conversion]*100. For the purposes of this invention, the term“selectivity” means molar selectivity, unless otherwise noted.

As used herein, the term “Gas Hourly Space Velocity” or “GHSV” in h⁻¹ isdefined as 60×[Total gas flow rate (mL/min)/catalyst bed volume (mL)].The total gas flow rate is calculated under Standard Temperature andPressure conditions (STP; 0° C. and 1 atm).

As used herein, the term “Liquid Hourly Space Velocity” or “LHSV” in h⁻¹is defined as 60×[Total liquid flow rate (mL/min)/catalyst bed volume(mL)].

II Catalysts

Unexpectedly, it has been found that catalysts containing mixedmonophosphates anions dehydrate hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof to acrylic acid, acrylic acidderivatives, or mixtures thereof with high: 1) yield and selectivity foracrylic acid, acrylic acid derivatives, or mixtures thereof, i.e., lowamount and few side products; 2) efficiency, i.e., performance in shortresidence time; and 3) longevity. Although not wishing to be bound byany theory, applicants hypothesize that the catalyst, which includes atleast monohydrogen monophosphate and dihydrogen monophosphate anions andtwo different cations, works as follows: the carboxylate group of thehydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof, associates with one or several cations, which in one embodimentis polyvalent, through one or both oxygen atoms, holding the moleculeonto the surface of the catalyst, deactivating it from decarbonylation,and activating the C—OH bond for elimination. Then, the resultingprotonated monophosphate anions dehydrate the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof by concertedprotonation of the hydroxyl group, removal of a proton from the methylgroup, and elimination of the protonated hydroxyl group as a molecule ofwater, generating acrylic acid, acrylic acid derivatives, or mixturesthereof and reactivating the catalyst. Furthermore, applicants believethat a specific protonation state of the monophosphate anions isimportant to facilitate the dehydration of hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof.

In one embodiment, the catalyst includes: (a) monohydrogen monophosphatedescribed by formula (I)

[HPO₄]²⁻  (I),

(b) dihydrogen monophosphate anions described by formula (II):

[H₂PO₄]⁻  (II),

and (c) at least two different cations, wherein the catalyst isessentially neutrally charged; and further, wherein the molar ratio ofsaid monohydrogen monophosphate anion to said dihydrogen monophosphateanion in the catalyst is between about 0.1 and about 10. In anotherembodiment, the molar ratio of monohydrogen monophosphate anion todihydrogen monophosphate anion is between about 0.2 and about 5. In yetanother embodiment, the molar ratio of monohydrogen monophosphate anionto dihydrogen monophosphate anion is about 1.

In one embodiment of the present invention, the catalyst includes themonophosphate salts described by both the formulae (III) and (IV):

M^(II)HPO₄  (III),

M^(I)H₂PO₄  (IV), and

wherein M^(I) is a monovalent cation and M^(II) is a divalent cation. Inanother embodiment, the molar ratio of M^(II)HPO₄ to M^(I)H₂PO₄ isbetween about 0.1 and about 10. In another embodiment, the molar ratioof M^(II)HPO₄ to M^(I)H₂PO₄ is between about 0.2 and about 5. In yetanother embodiment, the molar ratio of M^(II)HPO₄ to M^(I)H₂PO₄ is about1.

In one embodiment of the present invention, the catalyst includes amonophosphate salt described by the formula (V):

M^(II) _(2-x)M^(I) _(x)H_(x)(HPO₄)₂  (V),

wherein M^(I) is a monovalent cation and is a divalent cation; andwherein x is greater than about 0.2 and smaller than about 1.8. Inanother embodiment of the present invention, x is about 1.

In another embodiment, the monohydrogen monophosphate anion described byformula (I) is substituted by one or more phosphate anions described bythe formula [H_((1−v))P_((1+v))O_((4+3v))]^(2(1+v)−), wherein v isgreater or equal to zero and less or equal to 1.

In another embodiment, the dihydrogen monophosphate anion described byformula (II) is substituted by one or more phosphate anions described bythe formula [H_(2(1−v))PO_(4−v)]⁻, wherein v is greater or equal to zeroand less or equal to 1.

In one embodiment, the at least two different cations comprise (a) atleast one monovalent cation, and (b) at least one polyvalent cation. Inanother embodiment, the molar ratio of the monovalent cations to thepolyvalent cations is between about 0.1 and about 10. In yet anotherembodiment, the molar ratio of the monovalent cations to the polyvalentcations is between about 0.5 and about 5. In a further embodiment of thepresent invention, the molar ratio of the monovalent cations to thepolyvalent cations is about 1.

In one embodiment, the polyvalent cation is selected from the groupconsisting of divalent cations, trivalent cations, tetravalent cations,pentavalent cations, and mixtures thereof. Non-limiting examples ofmonovalent cations are Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Rb⁺, Tl⁺, andmixtures thereof. In one embodiment, the monovalent cation is selectedfrom the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and mixturesthereof. In another embodiment, the monovalent cation is Na⁺ or K⁺; andin yet another embodiment, the monovalent cation is K⁺. Non-limitingexamples of polyvalent cations are cations of the alkaline earth metals(i.e., Be, Mg, Ca, Sr, Ba, and Ra), transition metals (e.g. Y, Ti, Zr,V, Nb, Cr, Mo, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Ag, and Au), poormetals (e.g. Zn, Ga, Si, Ge, B, Al, In, Sb, Sn, Bi, and Pb), lanthanides(e.g. La and Ce), and actinides (e.g. Ac and Th). In one embodiment, thepolyvalent cation is selected from the group consisting of Be²⁺, Mg²⁺,Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Sn²⁺, Pb²⁺,Ti³⁺, Cr³⁺, Mn³⁺, Fe³⁺, Al³⁺, Ga³⁺, Y³⁺, In³⁺, Sb³⁺, Bi³⁺, Si⁴⁺, Ti⁴⁺,V⁴⁺, Ge⁴⁺, Mo⁴⁺, Pt⁴⁺, V⁵⁺, Nb⁵⁺, Sb⁵⁺, and mixtures thereof. In oneembodiment, the polyvalent cation is selected from the group consistingof Ca²⁺, Ba²⁺, Cu²⁺, Mn²⁺, Mn³⁺, and mixtures thereof. In anotherembodiment, the polyvalent cation is selected from the group consistingof Ca²⁺, Ba²⁺, Mn²⁺, and mixtures thereof. In yet another embodiment,the polyvalent cation is Ba²⁺.

The catalyst can include cations: (a) Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, ormixtures thereof; and (b) Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Fe²⁺,Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Sn²⁺, Pb²⁺, Ti³⁺, Cr³⁺, Mn³⁺, Fe³⁺, Al³⁺,Ga³⁺, Y³⁺, In³⁺, Sb³⁺, Bi³⁺, Si⁴⁺, Ti⁴⁺, V⁴⁺, Ge⁴⁺, Mo⁴⁺, Pt⁴⁺, V⁵⁺,Nb⁵⁺, Sb⁵⁺, or mixtures thereof. In one embodiment the catalystcomprises Li⁺, Na⁺, or K⁺ as monovalent cation, and Ca²⁺, Ba²⁺, Mn²⁺, orMn³⁺ as polyvalent cation. In another embodiment, the catalyst comprisesK⁺ as monovalent cation, and Ca²⁺, Ba²⁺, or Mn²⁺ as polyvalent cation.In yet another embodiment, the catalyst comprises K⁺ as the monovalentcation and Ba²+ as the polyvalent cation.

In one embodiment, the catalyst can include an inert support that isconstructed of a material selected from the group consisting ofsilicates, aluminates, carbons, metal oxides, and mixtures thereof.Alternatively, the carrier is inert relative to the reaction mixtureexpected to contact the catalyst. In the context of the reactionsexpressly described herein, in one embodiment the carrier is a lowsurface area silica or zirconia. When present, the carrier represents anamount of about 5 wt % to about 98 wt %, based on the total weight ofthe catalyst. Generally, a catalyst that includes an inert support canbe made by one of two exemplary methods: impregnation orco-precipitation. In the impregnation method, a suspension of the solidinert support is treated with a solution of a pre-catalyst, and theresulting material is then activated under conditions that will convertthe pre-catalyst to a more active state. In the co-precipitation method,a homogenous solution of the catalyst ingredients is precipitated by theaddition of additional ingredients.

III Catalyst Preparation Methods

In one embodiment of the present invention, the method of preparing thecatalyst includes mixing at least two phosphorus-containing compounds,wherein each said compound is described by one of formulae (VI) to(XXV), or any of the hydrated forms of said formulae:

M^(I) _(a)(H_(3-a)PO₄)  (VI)

M^(II) _(a)(H_(3-a)PO₄)₂  (VII)

M^(III) _(a)(H_(3-a)PO₄)₃  (VIII)

M^(IV) _(a)(H_(3-a)PO₄)₄  (IX)

M^(II) _(b)(OH)_(c)(PO₄)_(d)  (X)

M^(III) _(e)(OH)_(f)(PO₄)_(g)  (XI)

M^(II)M^(I)PO₄  (XII)

M^(III)M^(I) ₃(PO₄)₂  (XIII)

M^(IV) ₂M^(I)(PO₄)₃  (XIV)

M^(I) _(h)H_(4-h)P₂O₇  (XV)

M^(II) _(i)H_((4-2i))P₂O₇  (XVI)

M^(IV)P₂O₇  (XVII)

M^(III)M^(I)P₂O₇  (XVIII)

M^(I)H_(j)(PO₃)_((1+j))  (XIX)

M^(II)H_(j)(PO₃)_((2+j))  (XX)

M^(III)H_(j)(PO₃)_((3+j))  (XXI)

M^(IV)H_(j)(PO₃)_((4+j))  (XXII)

M^(II) _(k)M^(I) _(l)(PO₃)_(r)  (XXIII)

M^(III) _(q)M^(I) _(p)(PO₃)_(s)  (XXIV)

P₂O₅  (XXV)

wherein M^(I) is a monovalent cation; wherein M^(II) is a divalentcation; wherein M^(III) is a trivalent cation; wherein M^(N) is atetravalent cation; wherein a is 0, 1, 2, or 3; wherein h is 0, 1, 2, 3,or 4; wherein i is 0, 1, or 2; wherein j is 0 or any positive integer;and wherein b, c, d, e, f, g, k, l, m, n, p and q are any positiveintegers, such that the equations: 2b=c+3d, 3e=f+3g, r=2k+1, and s=3q+pare satisfied. In another embodiment, the method of preparing thecatalyst includes contacting the phosphorus-containing compounds aftermixing, with a gaseous mixture comprising water.

In one embodiment, the catalyst is prepared by mixing one or morephosphorus-containing compound of formula (VI), wherein said a is equalto 1, and one or more phosphorus-containing compound of formula (VII),wherein said a is equal to 2. In another embodiment, the catalyst isprepared by mixing KH₂PO₄ with BaHPO₄ or CaHPO₄.

In another embodiment, the catalyst is prepared by the steps including:(a) mixing one or more phosphorus-containing compound of formula (VI),wherein said a is equal to 1, and one or more phosphorus-containingcompound of formula (XVI), wherein said i is equal to 2; and (b)contacting the mixture of phosphorus-containing compounds with a gaseousmixture comprising water. In another embodiment, thephosphorus-containing compounds are KH₂PO₄ and Ba₂P₂O₇ or Ca₂P₂O₇.

In another embodiment, the catalyst is prepared by the steps including:(a) mixing one or more phosphorus-containing compounds of formula (VII),wherein said a is equal to 2, and one or more phosphorus-containingcompound of formula (XIX), wherein said j is equal to 0; and (b)contacting the mixture of the phosphorus-containing compounds with agaseous mixture comprising water. In another embodiment, thephosphorus-containing compounds are (KPO₃)_(w) and BaHPO₄ or CaHPO₄;wherein w is an integer greater than 2.

In yet another embodiment, the catalyst is prepared by the stepsincluding: (a) mixing one or more phosphorus-containing compounds offormula (XVI), wherein said i is equal to 2, and one or morephosphorus-containing compound of formula (XIX), wherein said j is equalto 0, and (b) contacting the mixture of the phosphorus-containingcompounds with a gaseous mixture comprising water. In anotherembodiment, the phosphorus-containing compounds are (KPO₃)_(w) andBa₂P₂O₇ or Ca₂P₂O₇; wherein w is an integer greater than 2.

In one embodiment of the present invention, the method of preparing thecatalyst includes mixing and heating: (a) at least onephosphorus-containing compound, wherein each said compound is describedby one of formulae (VI) to (XXV), or any of the hydrated forms of saidformulae:

M^(I) _(a)(H_(3-a)PO₄)  (VI)

M^(II) _(a)(H_(3-a)PO₄)₂  (VII)

M^(III) _(a)(H_(3-a)PO₄)₃  (VIII)

M^(IV) _(a)(H_(3-a)PO₄)₄  (IX)

M^(II) _(b)(OH)_(c)(PO₄)_(d)  (X)

M^(III) _(e)(OH)_(f)(PO₄)_(g)  (XI)

M^(II)M^(I)PO₄  (XII)

M^(III)M^(I) ₃(PO₄)₂  (XIII)

M^(IV) ₂M^(I)(PO₄)₃  (XIV)

M^(I) _(h)H_(4-h)P₂O₇  (XV)

M^(II) _(i)H_((4-2i))P₂O₇  (XVI)

M^(IV)P₂O₇  (XVII)

M^(III)M^(I)P₂O₇  (XVIII)

M^(I)H_(j)(PO₃)_((1+j))  (XIX)

M^(II)H_(j)(PO₃)_((2+j))  (XX)

M^(III)H_(j)(PO₃)_((3+j))  (XXI)

M^(IV)H_(j)(PO₃)_((4+j))  (XXII)

M^(II) _(k)M^(I) _(l)(PO₃)_(r)  (XXIII)

M^(III) _(q)M^(I) _(p)(PO₃)_(s)  (XXIV)

P₂O₅  (XXV)

wherein M^(I) is a monovalent cation; wherein M^(II) is a divalentcation; wherein M^(III) is a trivalent cation; wherein M^(IV) is atetravalent cation; wherein a is 0, 1, 2, or 3; wherein h is 0, 1, 2, 3,or 4; wherein i is 0, 1, or 2; wherein j is 0 or any positive integer;and wherein b, c, d, e, f, g, k, l, m, n, p and q are any positiveintegers, such that the equations: 2b=c+3d, 3e=f+3g, r=2k+l, and s=3q+pare satisfied; and (b) at least one non-phosphorus-containing compoundselected from the group consisting of nitrate salts, carbonate salts,acetate salts, metal oxides, chloride salts, sulfate salts, and metalhydroxides, wherein each said compound is described by one of theformulae (XXVI) to (L), or any of the hydrated forms of said formulae:

M^(I)NO₃  (XXVI)

M^(II)(NO₃)₂  (XXVII)

M^(III)(NO₃)₃  (XXVIII)

M^(I) ₂CO₃  (XXIX)

M^(II)CO₃  (XXX)

M^(III) ₂(CO₃)₃  (XXXI)

(CH₃COO)M^(I)  (XXXII)

(CH₃COO)₂M^(II)  (XXXIII)

(CH₃COO)₃M^(III)  (XXXIV)

(CH₃COO)₄M^(IV)  (XXXV)

M^(I) ₂O  (XXXVI)

M^(II)O  (XXXVII)

M^(III) ₂O₃  (XXXVIII)

M^(IV)O₂  (XXXIX)

M^(I)Cl  (XL)

M^(II)Cl₂  (XLI)

M^(III)Cl₃  (XLII)

M^(IV)Cl₄  (XLIII)

M^(I) ₂SO₄  (XLIV)

M^(II)SO₄  (XLV)

M^(III) ₂(SO₄)₃  (XLVI)

M^(IV)(SO₄)₂  (XLVII)

M^(I)OH  (XLVIII)

M^(II)(OH)₂  (XLIX)

M^(III)(OH)₃  (L).

In another embodiment, the non-phosphorus containing compounds can beselected from the group consisting of carboxylic acid-derived salts,halide salts, metal acetylacetonates, and metal alkoxides.

In another embodiment, the method of preparing the catalyst includescontacting the phosphorus-containing and the non-phosphorus-containingcompounds after mixing, with a gaseous mixture comprising water.

In one embodiment, the catalyst is prepared by the steps includingmixing and heating one or more phosphorus-containing compound of formula(VI), wherein said a is equal to 2, a phosphorus-containing compound offormula (VI), wherein said a is equal to 0 (i.e., phosphoric acid), andone or more nitrate salts of formula (XXVII). In another embodiment, thecatalyst is prepared by mixing and heating K₂HPO₄, H₃PO₄, and Ba(NO₃)₂.In yet another embodiment, the catalyst is prepared by mixing andheating K₂HPO₄, H₃PO₄, and Ca(NO₃)₂. In further another embodiment, thecatalyst is prepared by mixing and heating K₂HPO₄, H₃PO₄, andMn(NO₃)₂.4H₂O.

In one embodiment of the present invention, the method of preparing thecatalyst includes contacting: (a) a gaseous mixture comprising water,with (b) a mixture of compounds containing at least one condensedphosphate anion selected from the group consisting of formulae (LI) to(LIII),

[P_(n)O_(3n+1)]^((n+2)−)  (LI)

[P_(n)O_(3n)]^(n−)  (LII)

[P_((2m+n))O_((5m+3n))]^(n−)  (LIII)

wherein n is at least 2; wherein m is at least 1; wherein, said mixtureof compounds is essentially neutrally charged; and further, wherein themolar ratio of phosphorus to the monovalent and polyvalent cations inthe catalyst is between about 0.7 and about 1.7. In another embodiment,the molar ratio of phosphorus to the monovalent and polyvalent cationsis about 1.

In yet another embodiment, the catalyst is prepared by the stepsincluding contacting: (a) a gaseous mixture comprising water, with (b) amixture of compounds containing a condensed phosphate salt selected fromthe group consisting of Ba_(2−y-z)K_(2y)H_(2z)P₂O₇,Ca_(2−y-z)K_(2y)H_(2z)P₂O₇, Mn_(1−y−z)K_(1+3y)H_(3z)P₂O₇,Mn_(1−y-z)K_(2+2y)H_(2z)P₂O₇, and mixtures thereof; and (KPO₃)_(w);wherein y and z are greater or equal to 0 and less than about 0.5 and wis an integer greater than 2.

In one embodiment, the catalyst can include an inert support that isconstructed of a material selected from the group consisting ofsilicates, aluminates, carbons, metal oxides, and mixtures thereof.Alternatively, the carrier is inert relative to the reaction mixtureexpected to contact the catalyst. In another embodiment, the method ofpreparing the catalyst can further include mixing an inert support withthe catalyst before, during, or after the mixing of thephosphorus-containing compounds, wherein the inert support includessilicates, aluminates, carbons, metal oxides, and mixtures thereof. Inyet another embodiment, the method of preparing the catalyst can furtherinclude mixing an inert support with the catalyst before, during, orafter the mixing and heating of the phosphorus-containing compounds andthe non-phosphorus-containing compounds, wherein the inert supportincludes silicates, aluminates, carbons, metal oxides, and mixturesthereof.

Mixing of the phosphorus-containing compounds or thephosphorus-containing and non-phosphorus-containing compounds of thecatalyst can be performed by any method known to those skilled in theart, such as, by way of example and not limitation: solid mixing andco-precipitation. In the solid mixing method, the various components arephysically mixed together with optional grinding using any method knownto those skilled in the art, such as, by way of example and notlimitation, shear, extensional, kneading, extrusion, and others. In theco-precipitation method, an aqueous solution or suspension of thevarious components, including one or more of the phosphate compounds, isprepared, followed by optional filtration and heating to remove solventsand volatile materials (e.g., water, nitric acid, carbon dioxide,ammonia, or acetic acid). The heating is typically done using any methodknown to those skilled in the art, such as, by way of example and notlimitation, convection, conduction, radiation, microwave heating, andothers.

Following mixing, the catalyst is, in one embodiment, ground and sievedto provide a more uniform product. The particle size distribution of thecatalyst particles includes a particle span that, in one embodiment, isless than about 3; in another embodiment, the particle size distributionof the catalyst particles includes a particle span that is less thanabout 2; and in yet another embodiment, the particle size distributionof the catalyst particles includes a particle span that is less thanabout 1.5. In another embodiment of the invention, the catalyst issieved to a median particle size of about 50 μm to about 500 μm. Inanother embodiment of the invention, the catalyst is sieved to a medianparticle size of about 100 μm to about 200 μm.

The catalyst can be utilized to catalyze several chemical reactions.Non-limiting examples of reactions are: dehydration of hydroxypropionicacid to acrylic acid (as described in further detail below), dehydrationof glycerin to acrolein, dehydration of aliphatic alcohols to alkenes orolefins, dehydrogenation of aliphatic alcohols to ethers, otherdehydrogenations, hydrolyses, alkylations, dealkylations, oxidations,disproportionations, esterifications, cyclizations, isomerizations,condensations, aromatizations, polymerizations, and other reactions thatmay be apparent to those having ordinary skill in the art.

In one embodiment of the present invention, the catalyst is prepared bythe steps including combining BaHPO₄ and KH₂PO₄ in a molar ratio betweenabout 3:2 and about 2:3 to form a solid mixture, and grinding said solidmixture to produce the catalyst.

In another embodiment of the present invention, the catalyst is preparedby the steps including: (a) combining BaHPO₄ and KH₂PO₄ in a molar ratiobetween about 3:2 and about 2:3 to form a solid mixture; (b) grindingsaid solid mixture to produce a mixed powder; (c) calcining said mixedpowder at about 550° C. to produce a condensed phosphate mixture; and(d) contacting said condensed phosphate mixture with a gaseous mixturecomprising water and lactic acid at a temperature of about 350° C. and atotal pressure of about 25 bar to produce said catalyst, and wherein thepartial pressure of water in said gaseous mixture is about 12.5 bar.

In yet another embodiment of the present invention, the catalyst isprepared by the steps including: (a) combining K₂HPO₄, Ba(NO₃)₂, H₃PO₄,and water to form a wet mixture, wherein the molar ratio of Ba(NO₃)₂,K₂HPO₄, and H₃PO₄ is about 3:1:4; (b) heating said wet mixture to about80° C. with stirring until near dryness to form a wet solid; (c)calcining said wet solid stepwise at about 50° C., about 80° C., about120° C., and about 450° C. to about 550° C. to produce a dried solid;and (d) contacting said dried solid with a gaseous mixture comprisingwater and lactic acid at a temperature of about 350° C. and a totalpressure of about 25 bar to produce said catalyst, and wherein thepartial pressure of water in said gaseous mixture is about 12.5 bar.

IV Methods of Producing Acrylic Acid, Acrylic Acid Derivatives, orMixtures Thereof

A method for dehydrating hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof to acrylic acid, acrylic acidderivatives, or mixtures thereof is provided.

Alternative catalysts comprising anions selected from the groupconsisting of non-phosphorus-containing anions, heteropolyanions, andphosphate adducts, and at least two different cations, wherein thecatalyst is essentially neutrally charged, can be utilized fordehydrating hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof to acrylic acid, acrylic acid derivatives, or mixturesthereof. Non-limiting examples of non-phosphorus-containing anions arearsenates, condensed arsenates, nitrates, sulfates, borates, carbonates,chromates, vanadates, niobates, tantalates, selenates, and othermonomeric oxoanions or polyoxoanions that may be apparent to thosehaving ordinary skill in the art. Non-limiting examples ofheteropolyanions are heteropolyphosphates, such as arsenatophosphates,phosphoaluminates, phosphoborates, phosphocromates, phosphomolybdates,phosphosilicates, phosphosulfates, phosphotungstates, and others thatmay be apparent to those having ordinary skill in the art. Non-limitingexamples of phosphate adducts are adducts of phosphate anions withtelluric acid, halides, borates, carbonates, nitrates, sulfates,chromates, silicates, oxalates, mixtures thereof, or others that may beapparent to those having ordinary skill in the art.

Hydroxypropionic acid can be 3-hydroxypropionic acid, 2-hydroxypropionicacid (also called, lactic acid), or mixtures thereof. In one embodiment,the hydroxypropionic acid is lactic acid. Derivatives ofhydroxypropionic acid can be metal or ammonium salts of hydroxypropionicacid, alkyl esters of hydroxypropionic acid, hydroxypropionic acidoligomers, cyclic di-esters of hydroxypropionic acid, hydroxypropionicacid anhydride, or a mixture thereof. Non-limiting examples of metalsalts of hydroxypropionic acid are sodium hydroxypropionate, potassiumhydroxypropionate, and calcium hydroxypropionate. Non-limiting examplesof alkyl esters of hydroxypropionic acid are methyl hydroxypropionate,ethyl hydroxypropionate, butyl hydroxypropionate, 2-ethylhexylhydroxypropionate, or mixtures thereof. A non-limiting example of cyclicdi-esters of hydroxypropionic acid is dilactide.

Acrylic acid derivatives can be metal or ammonium salts of acrylic acid,alkyl esters of acrylic acid, acrylic acid oligomers, or mixturesthereof. Non-limiting examples of metal salts of acrylic acid are sodiumacrylate, potassium acrylate, and calcium acrylate. Non-limitingexamples of alkyl esters of acrylic acid are methyl acrylate, ethylacrylate, butyl acrylate, 2-ethylhexyl acrylate, or mixtures thereof.

The stream comprising hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof can include a liquid stream and aninert gas (i.e., a gas otherwise inert to the reaction mixture under theconditions of the method) that can be separately or jointly fed into anevaporation vessel upstream of the catalyst reactor for the stream tobecome gaseous. The liquid stream can include the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof and a diluent.Non-limiting examples of the diluent are water, methanol, ethanol,acetone, C3 to C8 linear and branched alcohols, C5 to C8 linear andbranched alkanes, ethyl acetate, non-volatile ethers (including diphenylether), and mixtures thereof. In one embodiment, the diluent compriseswater. In another embodiment, the liquid stream comprises an aqueoussolution of lactic acid or lactic acid derivatives selected from thegroup consisting of lactide, lactic acid oligomers, salts of lacticacid, and alkyl lactates. In one embodiment, the liquid stream includesfrom about 2 wt % to about 95 wt % lactic acid or lactic acidderivatives, based on the total weight of the liquid stream. In anotherembodiment, the liquid steam includes from about 5 wt % to about 50 wt %lactic acid or lactic acid derivatives, based on the total weight of theliquid stream. In another embodiment, the liquid stream includes fromabout 10 wt % to about 25 wt % lactic acid or lactic acid derivatives,based on the total weight of the liquid stream. In another embodiment,the liquid stream includes about 20 wt % lactic acid or lactic acidderivatives, based on the total weight of the liquid stream. In anotherembodiment, the liquid stream comprises an aqueous solution of lacticacid along with derivatives of lactic acid. In another embodiment, theliquid stream comprises less than about 30 wt % of lactic acidderivatives, based on the total weight of the liquid stream. In anotherembodiment, the liquid stream comprises less than about 10 wt % oflactic acid derivatives, based on the total weight of the liquid stream.In yet another embodiment, the liquid stream comprises less than about 5wt % of lactic acid derivatives, based on the total weight of the liquidstream.

The inert gas is a gas that is otherwise inert to the reaction mixtureunder the conditions of the method. Non-limiting examples of the inertgas are nitrogen, air, helium, argon, carbon dioxide, carbon monoxide,steam, and mixtures thereof. In one embodiment, the inert gas isnitrogen.

The stream comprising hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof can be in the form of a gaseous mixturewhen contacting the catalyst. In one embodiment, the concentration ofhydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof based on the total moles of said stream (calculated under STPconditions) is from about 0.5 mol % to about 50 mol %. In anotherembodiment, the concentration of hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof based on the total moles of saidstream (calculated under STP conditions) is from about 1 mol % to about10 mol %. In another embodiment, the concentration of hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof based onthe total moles of said stream (calculated under STP conditions) isbetween about 1.5 mol % to about 3.5 mol %. In yet another embodiment,the concentration of hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof based on the total moles of said stream(calculated under STP conditions) is about 2.5 mol %.

In one embodiment, the temperature at which said stream comprisinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof contacts the catalyst is between about 120° C. and about 700° C.In another embodiment, the temperature at which said stream comprisinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof contacts the catalyst is between about 150° C. and about 500° C.In another embodiment, the temperature at which said stream comprisinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof contacts the catalyst is between about 300° C. and about 450° C.In yet another embodiment, the temperature at which said streamcomprising hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof contacts the catalyst is between about 325° C. andabout 400° C.

In one embodiment, the stream comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof contacts thecatalyst at a GHSV between about 720 h⁻¹ and about 36,000 h⁻¹. Inanother embodiment, the stream comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof contacts thecatalyst at a GHSV between about 1,800 h⁻¹ to about 7,200 h⁻¹. Inanother embodiment, the stream comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof contacts thecatalyst at a GHSV about 3,600 h⁻¹.

In one embodiment, the stream comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof contacts thecatalyst at a pressure between about 0 psig and about 550 psig. Inanother embodiment, the stream comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof contacts thecatalyst at a pressure of about 360 psig.

In one embodiment the diluents comprises water and the partial pressureof water in the gaseous mixture is between about 10 psi and about 500psi. In another embodiment, the partial pressure of water in the gaseousmixture is between about 15 psi and about 320 psi. In yet anotherembodiment, the partial pressure of water in the gaseous mixture isabout 190 psi.

In one embodiment, the stream comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof contacts thecatalyst in a reactor having an interior surface comprising materialselected from the group consisting of quartz, borosilicate glass,silicon, hastelloy, inconel, manufactured sapphire, stainless steel, andmixtures thereof. In another embodiment, the stream comprisinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof contacts the catalyst in a reactor having an interior surfacecomprising material selected from the group consisting of quartz orborosilicate glass. In another embodiment, the stream comprisinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof contacts the catalyst in a reactor having an interior surfacecomprising borosilicate glass.

In one embodiment, the method includes contacting the catalyst with agaseous mixture comprising hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof under conditions sufficient to produceacrylic acid, acrylic acid derivatives, or mixtures thereof in a yieldof at least 50%. In another embodiment, the method includes contactingthe catalyst with a gaseous mixture comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof under conditionsare sufficient to produce acrylic acid, acrylic acid derivatives, ormixtures thereof in a yield of at least about 70% In another embodiment,the method includes contacting the catalyst with a gaseous mixturecomprising hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof under conditions are sufficient to produce acrylicacid, acrylic acid derivatives, or mixtures thereof in a yield of atleast about 80%. In another embodiment, the method conditions aresufficient to produce acrylic acid, acrylic acid derivatives, ormixtures thereof with a selectivity of at least about 50%. In anotherembodiment, the method conditions are sufficient to produce acrylicacid, acrylic acid derivatives, or mixtures thereof with a selectivityof at least about 70%. In another embodiment, the method conditions aresufficient to produce acrylic acid, acrylic acid derivatives, ormixtures thereof with a selectivity of at least about 80%. In anotherembodiment, the method conditions are sufficient to produce acrylicacid, acrylic acid derivatives, or mixtures thereof with propanoic acidas an impurity, wherein the propanoic acid selectivity is less thanabout 5%. In another embodiment, the method conditions are sufficient toproduce acrylic acid, acrylic acid derivatives, or mixtures thereof withpropanoic acid as an impurity, wherein the propanoic acid selectivity isless than about 1%. In another embodiment, the method conditions aresufficient to produce acrylic acid, acrylic acid derivatives, ormixtures thereof with a conversion of said hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof of more thanabout 50%. In another embodiment, the method conditions are sufficientto produce acrylic acid, acrylic acid derivatives, or mixtures thereofwith a conversion of said hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof of more than about 80%.

Among the benefits attainable by the foregoing embodiments is the lowyield of side products. In one embodiment, the conditions are sufficientto produce propionic acid in a yield of less than about 6% from lacticacid present in the gaseous mixture. In another embodiment, theconditions are sufficient to produce propionic acid in a yield of lessthan about 1%, from lactic acid present in the gaseous mixture. In oneembodiment, the conditions are sufficient to produce each of aceticacid, pyruvic acid, 1,2-propanediol, and 2,3-pentanedione in a yield ofless than about 2% from lactic acid present in the gaseous mixture. Inanother embodiment, the conditions are sufficient to produce each ofacetic acid, pyruvic acid, 1,2-propanediol, and 2,3-pentanedione in ayield of less than about 0.5%, from lactic acid present in the gaseousmixture. In one embodiment, the conditions are sufficient to produceacetaldehyde in a yield of less than about 8% from lactic acid presentin the gaseous mixture. In another embodiment, the conditions aresufficient to produce acetaldehyde in a yield of less than about 4% fromlactic acid present in the gaseous mixture. In another embodiment, theconditions are sufficient to produce acetaldehyde in a yield of lessthan about 3%, from lactic acid present in the gaseous mixture. Theseyields are believed to be, heretofore, unattainably low. Yet, thesebenefits are indeed achievable as further evidenced in the Examples setout below.

A method for dehydrating glycerin to acrolein is provided. The methodincludes contacting a glycerin containing stream with a catalystcomprising: (a) monohydrogen monophosphate and dihydrogen monophosphateanions described by formulae (I) and (II):

[HPO₄]²⁻  (I),

[H₂PO₄]⁻  (II), and

(b) at least two different cations, wherein the catalyst is essentiallyneutrally charged; and further, wherein the molar ratio of saidmonohydrogen monophosphate anion to said dihydrogen monophosphate anionin the catalyst is between about 0.1 and about 10, whereby acrolein isproduced as a result of said glycerin being contacted with the catalyst.Acrolein is an intermediate which can be converted to acrylic acid usingconditions similar to what are used today in the second oxidation stepin the propylene to acrylic acid process.

V Examples

The following examples are provided to illustrate the invention, but arenot intended to limit the scope thereof. Examples 1 through 3 describethe preparation of different mixed condensed phosphate catalysts inaccordance with various embodiments described above.

Example 1 Catalyst Preparation:

Barium monohydrogen phosphate, BaHPO₄ (20 g, 85.7 mmol, Sigma-AldrichCo., St. Louis, Mo.; catalog #31139) was combined with potassiumdihydrogen phosphate, KH₂PO₄ (7.8 g, 57.1 mmol, Sigma-Aldrich Co., St.Louis, Mo.; catalog #60216). The mixture was ground using a mortar andpestle until a fine powder was obtained. The material was dried at 105°C. for 2 h using a gravity convection oven to produce the catalyst.Finally, the material was analyzed by X-ray diffraction (XRD), allowingthe identification of BaHPO₄ and KH₂PO₄ as expected.

Catalyst Testing:

The catalyst was contacted with a gaseous mixture containing L-lacticacid (2.4 mol %), water (49.6 mol %), and nitrogen (48.0 mol %) usingthe reactor system described in Section VI. The reaction was performedat 350° C. and 360 psig, resulting in a partial pressure of water of 186psi. The results are summarized in Table 1 in Section VII.

Example 2 Catalyst Preparation:

Barium monohydrogen phosphate, BaHPO₄ (20 g, 85.7 mmol, Sigma-AldrichCo., St. Louis, Mo.; catalog #31139) was combined with potassiumdihydrogen phosphate, KH₂PO₄ (7.8 g, 57.1 mmol, Sigma-Aldrich Co., St.Louis, Mo.; catalog #60216). The mixture was ground using a mortar andpestle until a fine powder was obtained. The material was calcined at550° C. for 27 h using a gravity convection oven. After calcination, thematerial was left inside the oven until it cooled down by itself.Finally, the catalyst was ground and sieved to about 100 μm to about 200μm. The material was analyzed by XRD allowing the identification ofα-Ba₂P₂O₇ and KPO₃.

Catalyst Testing:

The catalyst was contacted with a gaseous mixture containing L-lacticacid (2.4 mol %), water (49.6 mol %), and nitrogen (48.0 mol %) usingthe reactor system described in Section VI. The reaction was performedat 350° C. and 360 psig, resulting in a partial pressure of water of 186psi. The results are summarized in Table 1 in Section VII.

Example 3 Catalyst Preparation:

An aqueous solution of barium nitrate, Ba(NO₃)₂ (3414 mL of a 0.08 g/mLstock solution, 1.04 mol, 99.999%; Sigma-Aldrich Co., St. Louis, Mo.;catalog #202754), was added to solid dibasic potassium phosphate, K₂HPO₄(60.7 g, 0.35 mol, ≧98%; Sigma-Aldrich Co., St. Louis, Mo.; catalog#P3786) at room temperature. Phosphoric acid, H₃PO₄ (98 mL of an 85 wt%, density=1.684 g/mL, 1.44 mol; Acros Organics, Geel, Belgium; catalog#295700010), was added to the slurry, providing a solution containingpotassium (K⁺, M^(I)) and barium (Ba²⁺, M^(II)) cations. The final pH ofthe suspension was about 1.6. The acid-containing suspension was thendried slowly in a glass beaker at 80° C. using a heating plate whilemagnetically stirring the suspension until the liquid was evaporated andthe material was almost completely dried. After evaporation, thematerial was transferred to a crushable ceramic. Heating was continuedin a oven with air circulation (N30/80 HA; Nabertherm GmbH, Lilienthal,Germany) at 50° C. for 2 h, then at 80° C. for 10 h (0.5° C./min ramp),120° C. for 2 hours (0.5° C./min ramp) to remove residual water followedby calcination at 450° C. for 4 hours (2° C./min ramp). Aftercalcination, the material was left inside the oven until it cooled downby itself at a temperature below 100° C. before it was taken out of theoven. Finally, the catalyst was ground and sieved to about 100 μm toabout 200 μm. The material was analyzed by XRD and energy dispersivespectroscopy coupled to scanning electron microscopy (EDS/SEM) allowingthe identification of σ-Ba₂P₂O₇, α-Ba₃P₄O₁₃, Ba(NO₃)₂, (KPO₃)_(w), andan additional phase presumably composed of a condensed phosphate withsignificant amounts of potassium and barium. Some incorporation of Kwithin all the Ba-containing phases was also detected. The molar ratiobetween phosphorus (P) and the cations (M^(I) and M^(II)) in thecondensed phosphate salts identified by XRD was about 1 to about 1.3.

Catalyst Testing:

The catalyst was contacted with a gaseous mixture containing L-lacticacid (2.3 mol %), water (49.9 mol %), and nitrogen (47.8 mol %) usingthe reactor system described in Section VI. The reaction was performedat 350° C. and 360 psig, resulting in a partial pressure of water of 187psi. The results are summarized in Table 1 in Section VII.

After the reaction was completed, the catalyst was cooled down to 236°C. while keeping the total pressure at 360 psig and flowing a gaseousmixture containing water (50.6 mol %) and nitrogen (49.4 mol %). Then,the temperature was decreased to 213° C. at a total pressure of 200 psigwhile flowing the same gaseous mixture, followed by additional coolingsteps to 180° C. at a total pressure of 100 psig and 125° C. at a totalpressure of 10 psig. After cooling, the catalyst was analyzed by XRD andEDS/SEM allowing the identification of BaHPO₄, a mixed phase withapparent chemical composition Ba_(2-x)K_(x)H_(x)(HPO₄)₂, and smallamounts of Ba(H₂PO₄)₂ and (KPO₃)_(w), wherein x is about 1 and w is aninteger greater than 2.

VI Test Procedures

XRD: The wide-angle data (WAXS) were collected on a STADI-P transmissionmode diffractometer (Stoe & Cie GmbH, Darmstadt, Germany). The generatorwas operated at 40 kV/40 mA, powering a copper anode long-fine-focus Cux-ray tube. The diffractometer incorporates an incident-beam curvedgermanium-crystal monochromator, standard incident-beam slit system, andan image plate-position sensitive detector with an angular range ofabout 124° 2θ. Data were collected in transmission mode. Samples weregently ground by hand using a mortar & pestle to fine powderconsistency, if necessary, before loading into the standard sampleholder for the instrument. Crystalline phases were identified using themost current powder diffraction database (from ICDD) using theSearch/Match routines in Jade (Materials Data, Inc. v9.4.2).

SEM/EDS: The dry powders were dispersed onto a double sided copper orcarbon tape which had been mounted onto a metal scanning electronmicroscope (SEM) substrate. Each specimen was coated with Au/Pd forapproximately 65-80 s using a Gatan Alto 2500 Cryo preparation chamber.SEM imaging & energy dispersive spectroscopy (EDS) mapping wereperformed using either a Hitachi S-4700 FE-SEM or Hitachi S-5200 in-lensFE-SEM (Hitachi Ltd., Tokyo, Japan) both equipped for EDS with BrukerXFlash 30 mm2 SDD detectors (Quantax 2000 system with 5030 detector;Bruker Corp., Billerica, Mass.). EDS mapping was performed using anaccelerating voltage of 10 kV in Analysis probe current mode. All mapswere generated using Bruker Esprit V1.9 software within the Hypermapmodule.

Reactor: A 13 inch (330 mm) long stainless steel glass lined tube (SGEAnalytical Science Pty Ltd., Ringwood, Australia) with a 4.0 mm internaldiameter (ID) was packed with glass wool (3 inch/76 mm bed length),topped by catalyst (1.6 cm³ bed volume, 5 inch/127 mm bed length) togive an 2.55 cm³ packed bed (8 inch/203 mm) and 1.6 cm³ (5 inch/127 mm)of free space at the top of the reactor. The tube was placed inside analuminum block and placed in a clam shell furnace series 3210 (AppliedTest Systems, Butler, Pa.) such as the top of the packed bed was alignedwith the top of the aluminum block. The reactor was set-up in adown-flow arrangement and was equipped with a Knauer Smartline 100 feedpump (Berlin, Germany), a Brooks 0254 gas flow controller (Hatfield,Pa.), a Brooks back pressure regulator, and a catch tank. The clam shellfurnace was heated such that the reactor wall temperature was keptconstant at about 350° C. during the course of the reaction. The reactorwas supplied with separate liquid and gas feeds that were mixed togetherbefore reaching the catalyst bed. The gas feed was composed of molecularnitrogen (N₂) at about 360 psig and at a flow of 45 mL/min. The liquidfeed was an aqueous solution of lactic acid (20 wt % L-lactic acid) andwas fed at 0.045 mL/min, After flowing through the reactor, the gaseousmixture was cooled and the liquids were collected in the catch tank foranalysis by off-line HPLC using an Agilent 1100 system (Santa Clara,Calif.) equipped with a diode array detector (DAD) and a Waters AtlantisT3 column (Catalog #186003748; Milford, Mass.) using methods generallyknown by those having ordinary skill in the art. The gaseous mixture wasanalyzed on-line by GC using an Agilent 7890 system (Santa Clara,Calif.) equipped with a FID detector and Varian CP-Para Bond Q column(Catalog #CP7351; Santa Clara, Calif.).

Reactor Feed: A solution (113.6 g) of biomass-derived lactic acid (88 wt%, Purac Corp., Lincolnshire, Ill.) was dissolved in distilled water(386.4 g) to provide a solution with an expected lactic acidconcentration of 20 wt %. This solution was heated at 95° C. to 100° C.for 12-30 hours. The resulting mixture was cooled and analyzed by HPLC(described above) against known weight standards.

VII Results

Table 1 summarizes the catalytic parameters obtained with the differentcatalysts described in Section V.

TABLE 1 Residence Time on LA AA AA CO CO₂ Time, Stream, Conversion,Yield, Selectivity, Yield, Yield, Example # (s) (min) (%) (%) (%) (%)(%) 1 1.4 172 93 ± 2 60 ± 2 64 ± 3 4 ± 0 3 ± 1 2 1.2 379 53 ± 3 39 ± 173 ± 2 3 ± 0 2 ± 0 3 1.0 328 90 ± 2 76 ± 1 85 ± 1 4 ± 1 3 ± 2

The foregoing description is given for clearness of understanding only,and no unnecessary limitations should be understood therefrom, asmodifications within the scope of the invention may be apparent to thosehaving ordinary skill in the art.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A catalyst comprising: a. monohydrogen monophosphate anions described by formula (I): [HPO₄]²⁻; b. dihydrogen monophosphate anions described by formula (II): [H₂PO₄]⁻; and c. at least two different cations; wherein the catalyst is essentially neutrally charged; and further, wherein the molar ratio of said monohydrogen monophosphate anion to said dihydrogen monophosphate anion in said catalyst is between about 0.1 and about
 10. 2. The catalyst of claim 1, wherein said at least two different cations comprise: a. at least one monovalent cation; and b. at least one polyvalent cation.
 3. The catalyst of claim 2, wherein said molar ratio of said monohydrogen monophosphate anion to said dihydrogen monophosphate anion in said catalyst is about
 1. 4. The catalyst of claim 2, wherein the molar ratio of said at least one monovalent cation to said at least one polyvalent cation in said catalyst is between about 0.1 and about
 10. 5. The catalyst of claim 4, wherein said molar ratio of said at least one monovalent cation to said at least one polyvalent cation in said catalyst is about
 1. 6. The catalyst of claim 2, wherein said at least one monovalent cation is selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and mixtures thereof.
 7. The catalyst of claim 6, wherein said at least one monovalent cation is K⁺.
 8. The catalyst of claim 2, wherein said at least one polyvalent cation is selected from the group consisting of divalent cations, trivalent cations, tetravalent cations, pentavalent cations, and mixtures thereof.
 9. The catalyst of claim 8, wherein said at least one polyvalent cation is selected from the group consisting of Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Sn²⁺, Pb²⁺, Ti³⁺, Cr³⁺, Mn³⁺, Fe³⁺, Al³⁺, Ga³⁺, Y³⁺, In³⁺, Sb³⁺, Bi³⁺, Si⁴⁺, Ti⁴⁺, V⁴⁺, Ge⁴⁺, Mo⁴⁺, Pt⁴⁺, V⁵⁺, Nb⁵⁺, Sb⁵⁺, and mixtures thereof.
 10. The catalyst of claim 9, wherein said at least one polyvalent cation is selected from the group consisting of Ba²⁺, Ca²⁺, and Mn²⁺.
 11. The catalyst of claim 2, wherein said catalyst comprises a monophosphate salt described by formula (III): M^(II)HPO₄  (III), and a monophosphate salt described by formula (IV): M^(I)H₂PO₄  (IV), wherein M^(I) is a monovalent cation and M^(II) is a divalent cation.
 12. The catalyst of claim 11, wherein the molar ratio of said monovalent cation to said divalent cation in said catalyst is between about 0.1 and about
 10. 13. The catalyst of claim 12, wherein said molar ratio of said monovalent cation to said polyvalent cation in said catalyst is about
 1. 14. The catalyst of claim 11, wherein said monovalent cation is selected from the group consisting of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and mixtures thereof; and wherein said divalent cation is selected from the group consisting of Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Sn²⁺, Pb²⁺, and mixtures thereof.
 15. The catalyst of claim 14, wherein said monovalent cation is K⁺; and wherein said divalent cation is selected from the group consisting of Ca²⁺, Ba²⁺, Mn²⁺, and mixtures thereof.
 16. The catalyst of claim 2, wherein said catalyst comprises a monophosphate salt described by formula (V): M^(II) _(2−x)M^(I) _(x)H_(x)(HPO₄)₂  (V), wherein M^(I) is a monovalent cation and M^(II) is a divalent cation; and wherein x is greater than about 0.2 and smaller than about 1.8.
 17. The catalyst of claim 16, wherein said x is about
 1. 18. The catalyst of claim 16, wherein said monovalent cation is K⁺; and wherein said divalent cation is selected from the group consisting of Ca²⁺, Ba²⁺, Mn²⁺, and mixtures thereof.
 19. The catalyst of claim 1, wherein said catalyst includes an inert support that is constructed of a material selected from the group consisting of silicates, aluminates, carbons, metal oxides, and mixtures thereof.
 20. A method of preparing the catalyst of claim 2 comprising mixing at least two phosphorus-containing compounds, wherein each said compound is described by one of formulae (VI) to (XXV), or any of the hydrated forms of said formulae: M^(I) _(a)(H_(3-a)PO₄)  (VI) M^(II) _(a)(H_(3-a)PO₄)₂  (VII) M^(III) _(a)(H_(3-a)PO₄)₃  (VIII) M^(IV) _(a)(H_(3-a)PO₄)₄  (IX) M^(II) _(b)(OH)_(c)(PO₄)_(d)  (X) M^(III) _(e)(OH)_(f)(PO₄)_(g)  (XI) M^(II)M^(I)PO₄  (XII) M^(III)M^(I) ₃(PO₄)₂  (XIII) M^(IV) ₂M^(I)(PO₄)₃  (XIV) M^(I) _(h)H_(4-h)P₂O₇  (XV) M^(II) _(i)H_((4-2i))P₂O₇  (XVI) M^(IV)P₂O₇  (XVII) M^(III)M^(I)P₂O₇  (XVIII) M^(I)H_(j)(PO₃)_((1+j))  (XIX) M^(II)H_(j)(PO₃)_((2+j))  (XX) M^(III)H_(j)(PO₃)_((3+j))  (XXI) M^(IV)H_(j)(PO₃)_((4+j))  (XXII) M^(II) _(k)M^(I) _(l)(PO₃)_(r)  (XXIII) M^(III) _(q)M^(I) _(p)(PO₃)_(s)  (XXIV) P₂O₅  (XXV) wherein M^(I) is a monovalent cation; wherein M^(II) is a divalent cation; wherein M^(III) is a trivalent cation; wherein M^(IV) is a tetravalent cation; wherein a is 0, 1, 2, or 3; wherein h is 0, 1, 2, 3, or 4; wherein i is 0, 1, or 2; wherein j is 0 or any positive integer; and wherein b, c, d, e, f, g, k, l, m, n, p and q are any positive integers, such that the equations: 2b=c+3d, 3e=f+3g, r=2k+1, and s=3q+p are satisfied.
 21. The method of claim 20 further comprising contacting said at least two different phosphorus-containing compounds after said mixing, with a gaseous mixture comprising water.
 22. The method of claim 20, wherein said phosphorus-containing compounds comprise a phosphorus-containing compound of formula (VI), wherein said a is equal to 1, and a phosphorus-containing compound of formula (VII), wherein said a is equal to
 2. 23. The method of claim 22, wherein said phosphorus-containing compounds comprise KH₂PO₄; and BaHPO₄ or CaHPO₄.
 24. The method of claim 21, wherein said phosphorus-containing compounds comprise a phosphorus-containing compound of formula (VI), wherein said a is equal to 1, and a phosphorus-containing compound of formula (XVI), wherein said i is equal to
 2. 25. The method of claim 24, wherein said phosphorus-containing compounds comprise KH₂PO₄; and Ba₂P₂O₇ or Ca₂P₂O₇.
 26. The method of claim 21, wherein said phosphorus-containing compounds comprise a phosphorus-containing compound of formula (VII), wherein said a is equal to 2, and a phosphorus-containing compound of formula (XIX), wherein said j is equal to
 0. 27. The method of claim 26, wherein said phosphorus-containing compounds comprise a) KPO₃; and b) BaHPO₄ or CaHPO₄.
 28. The method of claim 21, wherein said phosphorus-containing compounds comprise a phosphorus-containing compound of formula (XVI), wherein said i is equal to 2, and a phosphorus-containing compound of formula (XIX), wherein said j is equal to
 0. 29. The method of claim 28, wherein said phosphorus-containing compounds comprise a) KPO₃; and b) Ba₂P₂O₇ or Ca₂P₂O₇.
 30. The method of claim 20 further comprising mixing an inert support with said at least two phosphorus-containing compounds before, during, or after said mixing of the phosphorus-containing compounds, wherein said inert support is selected from the group consisting of silicates, aluminates, carbons, metal oxides, and mixtures thereof.
 31. A method of preparing the catalyst of claim 2 comprising mixing and heating: (a) at least one phosphorus-containing compound, wherein each said compound is described by one of formulae (VI) to (XXV), or any of the hydrated forms of said formulae: M^(I) _(a)(H_(3-a)PO₄)  (VI) M^(II) _(a)(H_(3-a)PO₄)₂  (VII) M^(III) _(a)(H_(3-a)PO₄)₃  (VIII) M^(IV) _(a)(H_(3-a)PO₄)₄  (IX) M^(II) _(b)(OH)_(c)(PO₄)_(d)  (X) M^(III) _(e)(OH)_(f)(PO₄)_(g)  (XI) M^(II)M^(I)PO₄  (XII) M^(III)M^(I) ₃(PO₄)₂  (XIII) M^(IV) ₂M^(I)(PO₄)₃  (XIV) M^(I) _(h)H_(4-h)P₂O₇  (XV) M^(II) _(i)H_((4-2i))P₂O₇  (XVI) M^(IV)P₂O₇  (XVII) M^(III)M^(I)P₂O₇  (XVIII) M^(I)H_(j)(PO₃)_((1+j))  (XIX) M^(II)H_(j)(PO₃)_((2+j))  (XX) M^(III)H_(j)(PO₃)_((3+j))  (XXI) M^(IV)H_(j)(PO₃)_((4+j))  (XXII) M^(II) _(k)M^(I) _(l)(PO₃)_(r)  (XXIII) M^(III) _(q)M^(I) _(p)(PO₃)_(s)  (XXIV) P₂O₅  (XXV) wherein M^(I) is a monovalent cation; wherein M^(II) is a divalent cation; wherein M^(III) is a trivalent cation; wherein M^(IV) is a tetravalent cation; wherein a is 0, 1, 2, or 3; wherein h is 0, 1, 2, 3, or 4; wherein i is 0, 1, or 2; wherein j is 0 or any positive integer; and wherein b, c, d, e, f, g, k, l, m, n, p and q are any positive integers, such that the equations: 2b=c+3d, 3e=f+3g, r=2k+l, and s=3q+p are satisfied; and (b) at least one non-phosphorus-containing compound selected from the group consisting of nitrate salts, carbonate salts, acetate salts, metal oxides, chloride salts, sulfate salts, and metal hydroxides, wherein each said compound is described by one of formulae (XXVI) to (L), or any of the hydrated forms of said formulae: M^(I)NO₃  (XXVI) M^(II)(NO₃)₂  (XXVII) M^(III)(NO₃)₃  (XXVIII) M^(I) ₂CO₃  (XXIX) M^(II)CO₃  (XXX) M^(III) ₂(CO₃)₃  (XXXI) (CH₃COO)M^(I)  (XXXII) (CH₃COO)₂M^(II)  (XXXIII) (CH₃COO)₃M^(III)  (XXXIV) (CH₃COO)₄M^(IV)  (XXXV) M^(I) ₂O  (XXXVI) M^(II)O  (XXXVII) M^(III) ₂O₃  (XXXVIII) M^(IV)O₂  (XXXIX) M^(I)Cl  (XL) M^(II)Cl₂  (XLI) M^(III)Cl₃  (XLII) M^(IV)Cl₄  (XLIII) M^(I) ₂SO₄  (XLIV) M^(II)SO₄  (XLV) M^(III) ₂(SO₄)₃  (XLVI) M^(IV)(SO₄)₂  (XLVII) M^(I)OH  (XLVIII) M^(II)(OH)₂  (XLIX) M^(III)(OH)₃  (L).
 32. The method of claim 31 further comprising contacting said at least one phosphorus-containing compound and said at least one non-phosphorus-containing compound after said mixing and heating, with a gaseous mixture comprising water.
 33. The method of claim 31, wherein said phosphorus-containing compounds comprise K₂HPO₄; and H₃PO₄; and wherein said nitrate salt is selected from the group consisting of Ba(NO₃)₂, Ca(NO₃)₂, Mn(NO₃)₂.4H₂O, and mixtures thereof.
 34. The method of claim 31 further comprising mixing an inert support with said at least one phosphorus-containing compound and said at least one non-phosphorus-containing compound, wherein said inert support is mixed before, during, or after said mixing of the compounds, and wherein said inert support is selected from the group consisting of silicates, aluminates, carbons, metal oxides, and mixtures thereof.
 35. A method of preparing the catalyst of claim 2 comprising contacting: (a) a gaseous mixture comprising water, with (b) a mixture of compounds comprising at least one condensed phosphate anion selected from the group consisting of formulae (LI) to (LIII), [P_(n)O_(3n+1)]^((n+2)−)  (LI) [P_(n)O_(3n)]^(n−)  (LII) [P_((2m+n))O_((5m+3n))]^(n−)  (LIII) wherein n is at least 2; wherein m is at least 1; wherein, said mixture of compounds is essentially neutrally charged; and further, wherein the molar ratio of phosphorus to said at least one monovalent cation and at least one polyvalent cation in said catalyst is between about 0.7 and about 1.7.
 36. The method of claim 35, wherein the molar ratio of phosphorus to said at least one monovalent cation and at least one polyvalent cation in said catalyst is about
 1. 37. The method of claim 35, wherein said mixture of compounds comprises a condensed phosphate salt selected from the group consisting of Ba_(2−y-z)K_(2y)H_(2z)P₂O₇, Ca_(2−y-z)K_(2y)H_(2z)P₂O₇, Mn_(1−y-z)K_(1+3y)H_(3z)P₂O₇, Mn_(1−y-z)K_(2+2y)H_(2z)P₂O₇, and mixtures thereof; and (KPO₃)_(w); wherein y and z are greater or equal to 0 and less than about 0.5 and w is an integer greater than
 2. 38. The method of claim 35, wherein said mixture of compounds further comprises an inert support that is constructed of a material selected from the group consisting of silicates, aluminates, carbons, metal oxides, and mixtures thereof.
 39. A method of preparing a catalyst comprising combining BaHPO₄ and KH₂PO₄ in a molar ratio between about 3:2 and about 2:3 to form a solid mixture, and grinding said solid mixture to produce said catalyst.
 40. A method of preparing a catalyst comprising: a. combining BaHPO₄ and KH₂PO₄ in a molar ratio between about 3:2 and about 2:3 to form a solid mixture; b. grinding said solid mixture to produce a mixed powder; c. calcining said mixed powder at about 550° C. to produce a condensed phosphate mixture; and d. contacting said condensed phosphate mixture with a gaseous mixture comprising water and lactic acid at a temperature of about 350° C. and a total pressure of about 25 bar to produce said catalyst, and wherein the partial pressure of water in said gaseous mixture is about 12.5 bar.
 41. A method of preparing a catalyst comprising the following steps: a. combining K₂HPO₄, Ba(NO₃)₂, H₃PO₄, and water to form a wet mixture, wherein the molar ratio of Ba(NO₃)₂, K₂HPO₄, and H₃PO₄ is about 3:1:4; b. heating said wet mixture to about 80° C. with stirring until near dryness to form a wet solid; c. calcining said wet solid stepwise at about 50° C., about 80° C., about 120° C., and about 450° C. to about 550° C. to produce a dried solid; and d. contacting said dried solid with a gaseous mixture comprising water and lactic acid at a temperature of about 350° C. and a total pressure of about 25 bar to produce said catalyst, and wherein the partial pressure of water in said gaseous mixture is about 12.5 bar. 